A variety of methods for producing colorizing images have been developed. Such methods include a dye-sublimation printing method, a thermal wax transfer printing method, an inkjet printing method, an electrophotographic printing method, and a thermally processed silver printing method.
Inkjet printers are used in a wide range of applications, including the advertising and broadcasting industries. It is desirable to improve printing quality and reduce the manufacturing costs of inkjet printers.
In the inkjet printing method, ink droplets are ejected from a nozzle of a printing head onto a printing medium, such as a paper sheet, thereby forming dots, which together form letters or images. The inkjet printing method is usually less expensive than other printing methods and high-quality color images can be printed. Ink used in the inkjet printing method may be prepared by dissolving or dispersing water-soluble dye or pigment in a solvent including water and a water-soluble organic solvent. The ink may further include a surfactant.
Inkjet printers may be piezoelectric-type inkjet printers, which eject ink using a piezoelectric device or thermal-type inkjet printers, which eject ink using a thermal device.
In thermal-type printers, the ink contained in an ink chamber of an inkjet printer head is evaporated by a heating device to generate bubbles. Ink droplets in the ink chamber are ejected onto a printing medium through an orifice, such as a nozzle. Therefore, a thermal-type inkjet printer includes an inkjet printer head, a heating device, which heats ink and may be positioned in the ink chamber. The printer also may have an operating circuit, such as a logic integrated circuit, operating the heating device.
Research into ink is being conducted to improve the throughput of inkjet printers and the clarity and brightness of images. For example, a pigment ink may increase the printing speed, improve color clarity and improve waterfastness of black ink. Pigment ink and dye ink should dry quickly on a paper medium. However, quick drying may clog an inkjet printer head. Clogging can be caused by ink, dust or paper. For a pigment ink in which pigment is dispersed in a water solvent, phase separation may occur in a drying process, thereby forming solid clumps. Such solid clumps formed on a nozzle surface cannot be easily removed and may affect the quality of printed images. When nozzle clogging or nozzle wetting occurs, ink ejection is hindered. The ejection speed of ink is also decreased and it becomes more difficult for ink droplets to be ejected.
Conventional methods of removing impurities from a nozzle surface are not effective for removing impurities remaining on the nozzle surface.